JP2008503423A - Method and system for producing granular material and method and system for reducing and measuring dust components in granular material - Google Patents

Abstract

The present invention relates to a method for producing granular polycrystalline silicon and a supply of granular polycrystalline silicon. The present invention also relates to a method and apparatus for measuring and removing dust components in granular polycrystalline silicon. In one aspect, the system has a vacuum port for drawing dust components from the polycrystalline silicon. Another system of the present invention has a baffle tube for receiving a flow of polycrystalline silicon. The measurement system has a manifold and a filter for separating and metering dust components from the polycrystalline silicon stream.

Description

  The present invention is for measuring and reducing dust components in granular materials, particularly granular polycrystalline materials used to grow semiconductor crystals and solar grade crystals. Relates to the method and apparatus.

  Granular polycrystalline silicon, such as CVD grown fluidized bed granular polycrystalline silicon, is typically placed in a transfer container and sent to a crystal growth facility. A conventional container contains 300 kg of granular polycrystalline silicon. Granular polycrystalline silicon generally has dimensions in the range of 400-1400 microns, and particulates with dimensions less than 10 microns are considered to be a dust component. As a practical matter, all containers contain a certain amount of dust components in them.

  Understanding the extent of dust components that can affect the yield of high quality semiconductor crystals has not been successful in the prior art. The mixing of a substantial amount of dust components with granular polycrystalline silicon can lead to undesirable defects such as “Loss of Zero Dislocation (LZD)” in high quality semiconductor crystals. It will increase the risk. Although relatively small batches of granular polycrystalline silicon in the prior art contained dust components in an acceptably low content, using today's continuous manufacturing methods, such low content polycrystalline silicon There is no reliable system for obtaining large quantities of Accordingly, there is a need for an improved method of measuring dust components, reducing dust components, and identifying the maximum dust component that can be tolerated in granular polycrystalline silicon.

  Briefly, one aspect of the present invention is a granular polycrystalline comprising forming granular polycrystalline silicon by chemical vapor deposition in a fluidized bed process and classifying the granular polycrystalline silicon by size. This is a method for continuously producing silicon. The dust component is removed from the granular polycrystalline silicon so that the dust component in the granular polycrystalline silicon has a mass (or weight) of less than 3 mg per 100 kg of the granular polycrystalline silicon. After removing the dust component, the granular polycrystalline silicon is packaged (eg, packaged for shipping).

  Another aspect of the present invention is a system for removing dust components from granular polycrystalline silicon. The system includes a vacuum source for aspirating and separating dust components from the polycrystalline silicon and a process vessel for receiving the granular polycrystalline silicon. A process vessel has opposing first and second ends, a polycrystalline silicon passage at the first end for passing granular polycrystalline silicon, a vacuum port communicating with the vacuum source. )have. The vacuum port is used to pour and introduce granular polycrystalline silicon from the process vessel so that the granular polycrystalline silicon does not block the vacuum port when the process vessel is rotated from an upright state. 2 is arranged adjacent to the end of the two. The system further includes a container for receiving granular polycrystalline silicon from the process vessel.

(Other description of the invention)
In another aspect, the process vessel is configured to accommodate the receipt of granular polycrystalline silicon, the opposing first and second ends, for passing the granular polycrystalline silicon. A polycrystalline silicon passage at the first end and a vacuum port communicating with the vacuum source. There is a closure for the decompression port so that when the process vessel is rotated from an upright position to pour and introduce the granular polycrystalline silicon from the process vessel, the granular polycrystalline silicon will not block the decompression port As such, a vacuum port is disposed adjacent to the second end of the process vessel.

  In some aspects of this summary, the vacuum port can be located on the sidewall of the process vessel. In this embodiment, the granular polycrystalline silicon can have a dust component of less than 3 mg per 10 kg of granular polycrystalline silicon received in the container. A valve may be connected to the polycrystalline silicon passage to selectively stop the flow of granular polycrystalline silicon through the polycrystalline silicon passage.

  Yet another aspect of the present invention has a polycrystalline silicon passage for discharging granular polycrystalline silicon at one end, and the granular polycrystalline at or adjacent to the opposite end. The present invention relates to a method for removing dust components from a predetermined amount of polycrystalline silicon material comprising granular polycrystalline silicon and dust components contained in a process vessel having a vacuum port spaced from the silicon. . This method involves pouring and introducing a predetermined amount of polycrystalline silicon material from a process vessel into a container, applying a vacuum through a vacuum port to aspirate dust components from around the polycrystalline silicon, and granular Preventing suction of the polycrystalline silicon.

  In some aspects of this summary, the pouring and sucking steps are repeated until the dust component is less than 3 mg per 10 kg of granular polycrystalline silicon received in the container. The vacuum suction step can be performed with water (pillar) at a lower pressure in the range of 1.3 to 5.1 cm than atmospheric pressure. The vacuum suction step can also be performed at a lower pressure in the range of 1.8 to 2.3 cm than the atmospheric pressure with a water column. Polycrystalline silicon can be poured and introduced at a flow rate of 10-12 kilograms / minute.

  In yet another aspect, a system for removing dust components from a granular polycrystalline silicon stream communicates fluid flow with the granular polycrystalline silicon feed to receive the granular polycrystalline silicon stream. And a baffle tube having a lower opening for discharging granular polycrystalline silicon. At least one baffle is provided below the upper opening, thereby changing the flow direction of the granular polycrystalline silicon so that the dust component entrained in the granular polycrystalline silicon is separated from the granular polycrystalline silicon. Promote separation. A vacuum source communicates with the upper opening, and sucks dust components accompanying the gas in a direction opposite to the flow direction of the granular polycrystalline silicon passing through the baffle tube.

  In some aspects of this summary, the system can further include a housing to which the baffle tube is attached. The housing can also have a funnel disposed above the baffle tube to shield the flow of polycrystalline silicon from vacuum suction. The housing can also have a vacuum port provided above the upper opening of the baffle tube to prevent suction of polycrystalline silicon through the vacuum port.

  In another aspect, a system for measuring a dust component in a flow of granular polycrystalline silicon includes a filter and a vacuum source for capturing the dust component used to measure the dust component. The manifold is a dust component collection chamber through which granular polycrystalline silicon passes, an outlet portion extending from the chamber, and an outlet portion communicating with the vacuum source for sucking the dust component from the chamber so that fluid can flow therethrough. And an air passage having at least one port extending from the chamber to an atmosphere surrounding the system. The filter is disposed between the outlet and the vacuum source. One port of the air passage is located adjacent to the outlet to draw (or suck) ambient air through the chamber, opposite to the direction of flow of the granular polycrystalline silicon, thereby The dust component exits the chamber through the opening and is then captured by the filter.

  In some aspects of this summary, the air passage may have six ports spaced equally within the range of about 2.5 cm of the outlet. The air passage can be located below the outlet and the filter can be formed of paper. The outlet portion can have a dimension in the range of about 0.25 cm to about 0.36 cm.

  In another method of the present invention, the dust component is measured from a flow of polycrystalline silicon material containing granular polycrystalline silicon and a dust component. The method includes a vacuum source, a manifold having a dust component collection chamber for flow of polycrystalline silicon material, and an outlet extending from the dust component collection chamber and in fluid communication with the vacuum source. It implements using the apparatus which has this. A filter is disposed between the outlet and the vacuum source and an air passage extends from the chamber to the atmosphere surrounding the system. The air passage has a port adjacent to the outlet. The method comprises the steps of first weighing the filter, and operating a vacuum source at a predetermined time period as the stream of polycrystalline silicon material flows through the chamber at a predetermined flow rate. Including doing in. When the reduced pressure source is activated, air and dust components are drawn toward the filter through the outlet, the filter captures the dust components, and the air passes to the reduced pressure source. Thereafter, the operation of the reduced pressure source is stopped, the second weight measurement after the operation of the reduced pressure source is performed, and the weight of the dust component captured by the filter is determined.

  In some aspects of the method, the vacuum source can be operated at a predetermined flow rate to draw in dust components of 10 microns or less. The predetermined time may be greater than about 30 seconds and less than about 90 seconds. A predetermined flow rate of polycrystalline silicon is preferably about 10 to 12 kg / min, and air is sucked into the air passage at a flow rate of about 2.5 liters / min.

  In yet another aspect, a supply of granular polycrystalline silicon is produced in a continuous production process. This granular polycrystalline silicon feed is suitable for producing semiconductor grade crystals. The granular polycrystalline silicon has an average diameter or width with dimensions in the range of 400-1400 microns. The granular polycrystalline silicon feed has a weight of at least about 3000 kg. The particulates of the dust component contained in (or entrained with) the granular polycrystalline silicon have a size of less than 10 microns and a weight of less than 3 mg per 100 kg of polycrystalline silicon. is doing. In some aspects of this summary, the feed is contained in multiple containers.

Some of the other features of the present invention are obvious and some are described in the following part of the specification.
The invention of this application will be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding parts throughout the drawings.

(Description of preferred embodiments of the invention)
With reference to FIGS. 1-2A, a system for removing dust components from granular polycrystalline silicon is indicated generally at 11. This system 11 generally separates (or sucks) dust components from the source container S for containing the granular polycrystalline silicon GP, the dust component D mixed in the granular polycrystalline silicon, and the granular polycrystalline silicon. ) And a process vessel P. For the purposes of this description, when the polycrystalline silicon material is processed, the dust component D is formed by polycrystalline silicon particles that are small enough to float easily in the air. Generally, these particulates have dimensions of 10 microns or less.

  The source container S contains a bulk supply of granular polycrystalline silicon GP (in a broad sense, granular material). In general, the source container S has a cylindrical shape, has an upper end portion 21 having a conical shape, and has an opening 23 (a polycrystalline silicon passage in a broad sense) at the center thereof. Yes.

  The process vessel P is substantially the same as the source vessel S, but the process vessel is adjacent to the vessel second end 27 on the side of the vessel (lower end when the vessel is upright). Thus, it is different that the pressure reducing port 25 is changed. In this embodiment, when the container P is turned over, the port 25 is provided above the level of the granular polycrystalline silicon so that the port is not blocked by the granular polycrystalline silicon (FIG. 2A). When the container is erected as shown in FIG. 1, a closure 29 for holding the granular polycrystalline silicon inside the container can be attached to the decompression port 25. The decompression port 25 can have a conventional quick-connector so that the hose can be quickly connected. Note that the port 25 can also be located at other parts of the container, for example at the upper end. The port can also extend from a second opening at the upper (first) end, for example extending from this opening through the polycrystalline polysilicon to the adjacent lower (second) end. It is also conceivable to have a tube.

  The decompression source V has a pump 31 for drawing a vacuum (or suctioning for decompression) and a decompression hose 33 for connecting the pump to the container P. The reduced pressure source V can have a filter (not shown) to prevent the dust component D from entering the pump or squeezing around the system 11.

  In one method of removing the dust component D from the polycrystalline silicon material in the source container S, the opening 23 of the source container S is provided with a valve 37 such as an “angle of repose (AOR)” valve. It is attached. The source vessel S is turned over and attached to an arm 39 extending from the vertical post 41 (as shown in FIG. 1), and a valve 37 is connected to the process vessel P. When the valve is opened, the granular polycrystalline silicon GP and the dust component D flow from the source container into the process container. After the source container S is emptied, the valve 37 is reattached between both containers, both containers are overturned, and the two containers are in the state shown in FIG. The configuration of FIG. 2 is the same as the configuration of FIG. 1 except that the decompression hose 33 is connected to the decompression port 25. When the valve 37 is opened and the granular polycrystalline silicon GP and the dust component D flow back to the source container S, the dust component D that can float in the air is sucked from around the polycrystalline silicon by decompression. Note that depressurization creates a reverse flow of gas at or near the opening 23 of the process vessel P. The reverse flow of the gas generally serves to suck in the dust component D that may float in the air from around the polycrystalline polycrystalline silicon GP at or near the opening. The dust component D that can float in the air is sucked and drawn out of the process container P, thereby preventing the dust component from entering the source container S again.

  In one embodiment, the reduced pressure source is set to apply a reduced pressure such that the granular polycrystalline silicon GP flows out of the process vessel P at a flow rate of about 10 kg / min. The exact vacuum required to produce such a flow will vary depending on various factors, such as the size of the opening 23 and the size of the process vessel P. A suitable method for finding an appropriate degree of decompression is to start the process at such a pressure that the granular polycrystalline silicon GP does not flow out of the process vessel P and effectively treat the dust component D in the polycrystalline silicon material. And the degree of decompression is lowered until the granular polycrystalline silicon GP flows at a sufficient flow rate that can be significantly reduced. The degree of depressurization varies for different systems and can vary from sub-atmospheric pressure to a water column of about 1.3-5.1 cm. However, once the appropriate pressure for a particular system is determined, it is not necessary to vary that pressure.

  Referring to FIG. 3, another system 51 for removing the dust component D from the granular polycrystalline silicon GP comprises a housing 53 to which a funnel 55, a baffle tube 57, and a decompression port 59 are attached. Has been. The housing 53 is attached to a lower position of the valve 37, and the valve 37 is connected to the source container S in the form shown in FIG. A funnel 55 is attached to the upper portion of the housing 53. The funnel 55 has a wide inlet 61 for receiving granular polycrystalline silicon and a conical portion 62 that narrows toward the lower portion 63. The baffle tube 57 has an upper opening 65 for receiving the outlet portion of the funnel 55, a baffle 67 disposed immediately below the outlet portion, and the granular polycrystalline silicon GP to another container (not shown). And a lower opening 69 for discharging. The baffle 67 is angled downward from the inner wall of the tube and extends across the baffle tube 57 to its middle. The baffle 67 is provided in a shape and arrangement that repeatedly changes the direction of the flow of the granular polycrystalline silicon GP through the tube 57. Therefore, the baffle 67 is entrained in the granular polycrystalline silicon or is granular. It is promoted that the dust component D adhering to the particle is separated from the granular polycrystalline silicon and floats in the air. The dust component that can float in the air is sucked upward from the baffle tube 57 by decompression. Although four baffles are shown in the figure, the scope of the invention includes the use of various numbers of baffles. Other types of baffles are also considered to be within the scope of this invention.

  The decompression port 59 has a first end 71 connected to the upper portion of the housing 53 and is angled downward toward a second end 73 that receives the hose 33 from the decompression source V. It extends. The first end 71 of the decompression port 59 is disposed adjacent to the funnel 55 and above the upper opening 65 of the baffle tube 57, and the decompression port 59 is disposed at a distance from the upper opening 65. The funnel 55 is disposed between the flow of granular polycrystalline silicon and the decompression port 59. In this way, the flow of granular polycrystalline silicon is shielded from decompression, thereby preventing particulates from being sucked into the decompression. A counterflow of air opposite to the direction of the flow of polycrystalline silicon is formed by the reduced pressure so that only the dust component D that can float in the air is sucked by the reduced pressure. The decompression port 59, the funnel 55 and the baffle tube 57 can each be attached to the housing 53 by any suitable method, for example, by welding or forming integrally in the housing as a one-piece system. Please note that. Similarly, the primary function of the funnel 55 is to shield the granular polycrystalline silicon GP from depressurization, and the funnel could be replaced by a tube or channel instead of a conical shaped funnel.

  In the method using system 51, vacuum source V is activated. When the valve 37 is opened, the granular polycrystalline silicon GP flows through the funnel 55 and the baffle tube 57. The reduced pressure source V is activated so that a substantial portion of the dust component D is drawn around the granular polycrystalline silicon GP. The method of this application is sufficient to reduce the dust component D in most granular polycrystalline silicon. In particular, according to this arrangement, dust component characteristics such that, as measured according to the method described below, the discharged granular polycrystalline silicon GP is, for example, less than 3 milligrams of dust component per 10 kilograms of granular polycrystalline silicon. In order to have a value, a sufficient amount of dust component that can be suspended from the flow of polycrystalline silicon is extracted. As described below, the crystal pulling operation is largely unaffected by the presence of dust components at such low levels.

  Referring to FIG. 4, a system 81 for measuring a dust component D in a flow of granular polycrystalline silicon GP includes a manifold generally designated 83 and generally designated 85 to capture powder. And a filter assembly as shown. The manifold 83 has a flow through the dust component collection chamber 87 to allow the granular polycrystalline silicon flow to pass through. The chamber 87 communicates with an upper container 89 such as the source container S or the process container P so that the fluid flows, and discharges the flow to the container 91 such as the supply hopper 117 or another container. The dust component outlet 93 extends upward through the manifold 83 from the dust component collection chamber 87 to the junction with the filter assembly 85. The filter housing 97 of the filter assembly 85 has a generally tubular shape and receives a first end 99 that receives the outlet 93 of the manifold at the joint and a hose 103 that is connected to the vacuum source V. Second end 101. The filter 105 of the filter assembly 85 is held in the filter housing 97 and is therefore disposed between the outlet 93 and the reduced pressure source V. The filter 105 has a circular shape and is formed of a suitable material such as paper. A suitable filter assembly is a 37 mm diameter MILLIPORE® field monitor filter.

  The manifold 83 further has an air passage including six ports 107 (three are shown in FIG. 4) extending from the dust component collection chamber 87 into the atmosphere surrounding the manifold. Port 107 has suitable dimensions, for example, the port has an inner diameter in the range of about 0.89 mm to about 0.11 mm, and in one embodiment, an inner diameter of about 0.10 mm. The ports 107 are equally spaced around the dust collection chamber 87 and are adjacent to the outlet 93 (eg, within about 1.25 cm below the outlet or within the outlet). The ambient air is drawn through the port and through the dust component collection chamber in a direction opposite to the direction of flow of the granular polycrystalline silicon GP. . Therefore, the reduced pressure facilitates the dust component D to exit the chamber 87 through the outlet 93 and then be captured in the filter 105.

  The vacuum pump flow rate and the dimensions (dimensions) of the outlet portion 93 of the manifold 83 are selected such that the silicon dust component particulates pass through the outlet portion and into the filter 105. The flow rate set for silicon dust components with a diameter of less than 10 microns is approximately 0.61 cm / sec (Perry's Chemical Engineers Handbook, Revised 5th Ed.) Fig. 5-80). From the set flow rate, the outlet diameter ranges from about 0.25 to about 0.36 centimeters, for example about 0.30 cm, and the pump flow rate is about 2.50 liters / minute. Note that the dust component collection chamber 87 preferably has a diameter of about 3.8 cm.

  In the method of measuring the relative amount of dust component D in the flow of granular polycrystalline silicon GP, filter assembly 85 is weighed and then manifold 83 and the configuration shown in FIG. Connected to vacuum source V. Note that either filter 105 or filter assembly 85 may be weighed. The valve is opened, the manifold 83 is passed through the flow of the granular polycrystalline silicon GP at a predetermined flow rate, the vacuum source V is operated, and the dust component is sucked through the filter 105. After a predetermined sampling time, the vacuum source V is stopped (the polycrystalline silicon flow may be stopped). The filter assembly 85 is disconnected from the vacuum source V and the manifold 83, and a second weight measurement is performed. The first weight measurement is subtracted from the second weight measurement to determine the weight of the dust component particulates collected within the sampling time. The mass flow rate of the granular polycrystalline silicon GP through the manifold 83 is known. The obtained measured value is given by the relationship (or term) of the weight of the dust component per weight of the granular polycrystalline silicon, for example, the number of mg of the dust component per kg of the granular polycrystalline silicon. In this way, not all dust components are removed from the granular polycrystalline silicon, so the measured value is a relative measure of the dust component D in the granular polycrystalline silicon GP. Applicants have found that accurate comparative measurements of dust components can be made under the following conditions: sampling time 1 minute ± 5 seconds, flow rate of granular polycrystalline silicon through the dust component collection chamber approximately 10 kg / min ± 0 .10, pump flow rate of about 2.50 liters / minute.

The measuring method of the present invention can be used at various points in the production stage, the delivery stage and the use stage of the granular polycrystalline silicon GP. In particular, this method is used at the point where granular polycrystalline silicon is used, that is, at the point where the crystal pulling apparatus enters the crystal pulling equipment (“Incoming Quality Assurance (IQA))” or at the granular polycrystal. It can also be used during the production of crystalline silicon. This method
(1) As an auxiliary in quantifying the influence of the dust component D on the crystal yield,
(2) accept or reject granular polycrystalline silicon supplied to the container (container) based on the dust component in the container;
(3) Only those having a dust component less than a predetermined characteristic value are supplied to a crystal pulling device used in a crystal growth process that is sensitive to (or dust-sensitive) dust components. It provides a relative dust component measurement that can be used to classify receiving containers.

  As described above, the prior art has not succeeded in grasping the extent to which the dust component D affects the yield of high quality semiconductor crystals and the extent to which the dust component affects the advancing crystal growth apparatus. . When the granular polycrystalline silicon GP is transferred from the container to the feeder system of the crystal growth apparatus, the dust component is also sent to the feeder system. Dust component D collects and settles from the feeder system to the surface of the hot zone of the crystal growth apparatus, in particular to the cooler surface in the improved “closed” crystal growth apparatus. Thereafter, the dust component D may come into contact with the crystal or silicon melt near the crystal / melt interface. Such a contact would significantly increase the risk of defects such as “loss of zero dislocations (LZD)” in high quality semiconductor crystals. Such crystals, and the improved crystal growth equipment used to grow the crystals, have been found to be “dust-sensitive”.

  Applicant has shown that when the dust component level in the granular polycrystalline silicon used for crystal growth is consistently maintained at a characteristic value of less than 3 mg per 10 kg of granular polycrystalline silicon, as shown in FIG. We have found that the yield (or yield) of "zero dislocations" (or no dislocations) crystals increases significantly more than expected. In FIG. 5, the yield is the portion where zero dislocations exist for a crystal length of 300 mm. FIG. 5 shows that there was consistently significant variation in yield prior to using the characteristic values (data in the seven terms preceding the “Dust Component Test” term). That is, for the sample of about 30 crystals, the length of the zero dislocation crystal grown in each crystal varied in any range from about 0 to about 76.2 cm. For example, in the sample of the seventh term, the yield fluctuated in the range of 0 to about 76.2 cm for the sample of about 32 crystals. Using characteristic values (dust component test term) yields ranged from about 71 to about 79 cm for about 29 crystal samples. During the dust component test, other variables related to crystal growth remained unchanged. Accordingly, Applicants believe that this surprising increase in yield has occurred by using granular polycrystalline silicon within its characteristic values.

  In order to ensure the quality of the granular polycrystalline silicon supplied to the crystal pulling apparatus, any of the above-described dust component removing step and the measuring method, or a combination thereof can be employed. For example, the dust component D in the source container can be measured and classified according to the dust component measurement method. A container having the lowest dust component can be used for crystal pulling applications that are most sensitive to the dust component. Alternatively, a container having a dust component D that exceeds a characteristic value can be “de-dusted” using the method described above. Furthermore, by implementing any of the methods of the dust collection component method in the manufacturing stage, it is possible to ensure that substantially the entire source container supplied to the crystal pulling equipment is below the dust component characteristic value.

  As explained below, the dust component removal method has been found to be more effective than the “gas classification” method commonly used for granular polycrystalline silicon production. Applicants have found that the gas classification method does not further filter out a sufficient amount of dust component D. The dust component often segregates (or is unevenly distributed) in some of the large hoppers used during manufacture to fill the transfer container. Such segregation will cause some containers to have a relatively low level of dust content, depending on whether the hopper was almost full or almost empty when the container was filled. On the other hand, other containers can result in having a relatively high level of dust components. During one sample period, about 25% of the containers received in the crystal growth facility had a dust component that exceeded the characteristic values described above. It has been found that the new dust component collection method of the present invention is sufficient to ensure that a fairly high proportion of granular polycrystalline silicon falls within the range of dust component characteristic values. This result is illustrated by the higher ZD crystal yield (or yield) shown in FIG.

Alternatively, particulate polycrystalline silicon dust component removal is performed as part of the manufacturing and packaging process. Referring to FIG. 6, a manufacturing and packaging system 109 is shown, which includes a conventional fluidized bed reactor 111, a conventional gas classifier 113, a conventional dehydrogenator 115, and dust component collection. A method system 51 is included. This system 109 is used in a continuous manufacturing method. The first step of this method is a conventional chemical vapor decomposition process (CVD), in which a polycrystalline silicon seed is periodically introduced into the reactor 111. More specifically, seeds are fed into the gas mixture flowing SiH ₄ + H ₂ at a temperature suitable to decompose SiH ₄ into H ₂ gas and Si. Si precipitates on the polycrystalline silicon seed to produce granular polycrystalline silicon GP, which is then removed from the reactor 111. The granular polycrystalline silicon is transferred to gas sorter 113 for classification by particle size by suitable means (eg a portable hopper). The granular polycrystalline silicon is then subjected to dehydrogenation in the dehydrogenator 115. The granular polycrystalline silicon can also be subjected to the gas sorter multiple times before and / or after dehydrogenation.

During vapor deposition and dehydrogenation, the particulate matter collides with each other, or collides with the respective inner walls of the reactor 111 and the dehydrogenation device 115, thereby generating a dust component D. Dust components can also be generated in the reactor 111 by particulate nucleation and growth during SiH ₄ decomposition. In order to remove the dust component D, the particulate component is removed from the particulate polycrystalline silicon by placing the particulate polycrystalline silicon in a hopper 117 connected to the dust component removal system 51 according to the method described above. The system 51 supplies the granular polycrystalline silicon from which the dust component has been removed into the source container S. This method is suitable for use in supplying a substantial amount of particulate polycrystalline silicon from which dust components have been removed, for example at least 3000 kg, to a plurality of source containers (eg transfer containers). This allows the granular polycrystalline silicon to be packaged in a substantially dust-free (or dust-free) form and ready for shipment to the consumer. In this method, each source container will have less dust component than specified, so there is no need for dust component removal during use.

  It will be appreciated that other dust component removal systems may be used in place of or in addition to the system 51 of the present invention. For example, the system 11 can be used to change the hopper 117 to be similar to the process container P so that the dust component D is sucked from around the polycrystalline polycrystalline silicon. Moreover, a dust component removal system can also be employ | adopted between different processes in a manufacturing method, for example, before a dehydrogenation process.

(Example)
Two 300 kilogram source containers (or shipping drums) arrived at the crystal growth facility. The contents of the source vessel were placed in a process vessel having the configuration shown in FIG. 1 with the addition of the dust component measurement system of FIG. 4 attached to the lower side of the AOR valve. The level of the dust component in each container was measured using the method described above. The level of the dust component for the first container was 4.9 mg / 10 kg, and the level of the dust component for the second container was 7.5 mg / 10 kg (ie, out of the characteristic value range). Measured.

  The dust component D was removed from the container using the system 11 of FIG. 2, and the measurement system of FIG. 4 was reattached to the lower side of the AOR valve. The depressurization step was performed at a pressure lower than the atmospheric pressure in the range of 1.8 to 2.3 cm with a water column, and at that time, granular polycrystalline silicon was allowed to flow at a relatively effective flow rate of about 10 kg / min. The dust component in the first container was reduced to 0.8 mg / 10 kg, and the dust component in the second container was reduced to 1.0 mg / 10 kg. It took about 2 hours to move and inject granular polycrystalline silicon from the source container to the process container and, conversely, to move and inject granular polycrystalline silicon from the process container to the source container.

  In another example shown in FIG. 7, the “dust component removal” operation was performed on the twelve 300 kilogram source containers received in the crystal growth facility using the “tumbled container” system of FIG. 2. When measured when supplying to the equipment of the above-described method, all containers had a dust component value higher than the 3 mg / lOkg characteristic value as shown in FIG. After one dust component removal cycle, the dust component value in each container was lower than the characteristic value. In another example shown in FIG. 8, a “dust component removal” operation was performed on several 300 kilogram source containers received in the crystal growth facility using the “tumbled container” system of FIG. When measured according to the above-described method, as shown in FIG. 8, about 27% of the containers had a dust component value higher than the 3 mg / lOkg characteristic value when supplied to the facility. After one dust component removal cycle, the dust component value in each container was lower than the characteristic value.

  In order to prevent contamination of the granular polycrystalline silicon GP processed by the systems 11 and 51, all system elements in contact with the high speed granular polycrystalline silicon will depend on the materials chosen to maintain the system's uncontaminated performance. Coated or formed by such materials. Such materials include, but are not limited to, quartz coating materials, silicon coating materials, solid silicon materials, and solid silicon carbide materials. In general, the coating is applied to a stainless steel substrate. Other materials suitable for antifouling property values are also contemplated as being within the scope of the present invention. For the low speed part of the device, TEFLON® or TEFZEL (TEFZEL) (available from EI du Pont de Nemours and Company (Wilmington, Delaware, USA)) An acceptable antifouling property value can be provided by the registered trademark coating. In addition, in order to maintain the purity of the granular polycrystalline silicon when supplied to the crystal growth facility, the source container is filled with non-contaminating argon, but in a controlled humidity environment, Argon need not be held there.

  Regarding the element of the present invention or the element of the preferred embodiment thereof, the description “one (a)”, “one (an)”, “the (the)” and “said” is one or more. It means that there is an element. The phrases “comprising”, “including”, and “having” are inclusive meaning that there may be elements other than the elements mentioned. Is intended to be.

  Since various modifications can be made to the above-described configurations, products, and methods without departing from the scope of the present invention, all matters described in the specification and those shown in the accompanying drawings are examples. It is intended and not intended to be limiting.

FIG. 1 is a perspective view showing a process vessel, a valve, and a source vessel, and the source vessel is shown in an upside down direction for introducing granular polycrystalline silicon through the valve and into the process vessel. Yes. FIG. 2 is a perspective view similar to FIG. 1 except that the position of the process vessel and the source vessel are reversed and schematically shows a reduced pressure source for removing dust components from the granular polycrystalline silicon. FIG. 2A is a schematic cross-sectional view of the process vessel observed along line 2A-2A in FIG. FIG. 3 is a schematic cross-sectional view showing a portion of another system for removing dust components from granular polycrystalline silicon. It is typical sectional drawing which shows a part of system for measuring a dust component. FIG. 5 is a graph showing the yield of zero dislocation crystals. FIG. 6 is a schematic diagram of a granular polycrystalline silicon manufacturing and packaging system. FIG. 7 is a graph of dust components contained in a sample of the source container. FIG. 8 is a graph of dust components contained in a sample of the source container.

Claims (10)

Forming granular polycrystalline silicon by chemical vapor deposition in a fluidized bed process;
Classifying the granular polycrystalline silicon according to dimensions;
Removing the dust component from the granular polycrystalline silicon so that the dust component in the granular polycrystalline silicon has a mass of less than 3 mg per 100 kg of polycrystalline silicon;
A method for continuously producing granular polycrystalline silicon comprising the step of packaging granular polycrystalline silicon after removing dust components.   The method of claim 1, wherein the dust component removal step comprises feeding a polycrystalline silicon material comprising granular polycrystalline silicon and a dust component to the baffle tube.   3. The method of claim 2, wherein the dust component removal step comprises applying a vacuum to the baffle tube to suck the dust component from the polycrystalline silicon material.   The method further includes the step of transferring the polycrystalline silicon material to a hopper before removing the dust component, wherein the dust component removing step applies a reduced pressure to the polycrystalline silicon material in the hopper to remove the dust component therefrom. The method of claim 2 comprising:   The method of claim 4 further comprising the step of dehydrogenating the particulate polycrystalline silicon material. A vacuum source for separating dust components from granular polycrystalline silicon;
A process vessel adapted to receive granular polycrystalline silicon, the first and second ends facing each other, the poly at the first end for passing granular polycrystalline silicon A process vessel having a crystalline silicon passageway and a vacuum port in communication with the vacuum source; and removing dust components from the granular polycrystalline silicon comprising a container for receiving the granular polycrystalline silicon from the process vessel A system for
The vacuum port is a second port in the process vessel so that the granular polycrystalline silicon does not block the vacuum port when the process vessel is rotated from an upright position to pour the granular polycrystalline silicon from the process vessel. System located adjacent to the end of the.   The system of claim 6, wherein the vacuum port is located on a side wall of the process vessel.   The system of claim 6 in combination with granular polycrystalline silicon in which a dust component is present at less than 3 mg per 10 kg of granular polycrystalline silicon received in the container.   The system of claim 6, further comprising a valve in communication with the polycrystalline silicon passage to selectively stop the flow of granular polycrystalline silicon through the polycrystalline silicon passage.   The system according to claim 9, wherein the valve is a repose angle valve.

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